CVE-2021-47364

In the Linux kernel, the following vulnerability has been resolved:

comedi: Fix memory leak in compat_insnlist()

compat_insnlist() handles the 32-bit version of the COMEDI_INSNLIST ioctl (whenwhen CONFIG_COMPAT is enabled). It allocates memory to temporarily hold an array of struct comedi_insn converted from the 32-bit version in user space. This memory is only being freed if there is a fault while filling the array, otherwise it is leaked.

Add a call to kfree() to fix the leak.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/8d6a21e4cd6a319b0662cbe4ad6199e276ac776a
• https://git.kernel.org/stable/c/bb509a6ffed2c8b0950f637ab5779aa818ed1596
• https://git.kernel.org/stable/c/f217b6c1e28ed0b353634ce4d92a155b80bd1671
• https://git.kernel.org/stable/c/8d6a21e4cd6a319b0662cbe4ad6199e276ac776a
• https://git.kernel.org/stable/c/bb509a6ffed2c8b0950f637ab5779aa818ed1596
• https://git.kernel.org/stable/c/f217b6c1e28ed0b353634ce4d92a155b80bd1671